In a conventional magnetic read/write apparatus of this type, and in particular, in a magnetic read/write apparatus for a compact electronic camera, separate read using separate read and write decks, neither read nor re-write can be performed immediately after the write operation. Therefore, the apparatuses cannot satisfy the user's demand for read and re-write, if necessary, immediately after the writing of an image or the like. This also applies to digital data write. A magnetic read/write apparatus devised to solve this problem to a certain extent is known. The apparatus comprises a read/write head (hereinafter called R/W head) with integrally formed read and write heads and a read/write circuit, and, read and re-write can both be performed immediately after data write for digital data. Image information can also be read immediately after the write operation. Since an erase head is not provided, however, written data cannot be erased for rewrite, making re-write of image data immediately after the write operation impossible. The main reasons why the apparatus includes no erase head are as follows. First, overwrite can be performed in writing digital data, and an erase head is not necessary. Second, all parts must be small since the space available for mounting such parts is limited in a compact electronic camera, and a relatively large part such as an erase head, cannot be used.
In addition, even if space is available and an erase head can be mounted in addition to a R/W head, the following problem is still presented. When the two heads are assembled in a compact magnetic disk apparatus using a compact magnetic disk having a diameter of about 2 inches as a recording medium, it is extremely difficult to set the head positions so that both heads maintain good head touch. As a result, the so-called spacing loss increases. When high-density write is performed with write wavelengths in the order of 0.5 .mu.m or less, the spacing loss due to poor head touch must be reduced to a minimum. However, since good head touch for each head cannot be obtained as described above, the spacing loss increases and high-density write cannot be performed.
A frame write mode using 2 tracks is known as one image write scheme. When applied to a compact magnetic disk unit for recording in the frame write mode, two erase heads must be included besides two R/W heads. Therefore, a total of 4 heads must be assembled in a limited deck space, and it is still difficult to obtain space for mounting the heads while maintaining good head touch for each head. In this manner, assembly of an erase head involves various difficulties. In practice, therefore, image information is erased by a separate erase unit. For this reason, the above-mentioned demand for read and re-write of an image or the like immediately after it has been written has not been satisfied.
The gap width and track width of an erase head must be larger than those of an R/W head. Crosstalk must also be considered if the erase head is too close to the R/W head. In view of this, it has been considered impossible to assemble erase and R/W heads together while still maintaining the read/write performance of the apparatus.
It is, therefore, an object of the present invention to provide a compact composite magnetic head which offers good head touch, which can satisfactorily read and write various information such as image information without increasing crosstalk or spacing loss, which allows re-write immediately after write operation, and which is easy to manufacture.
It is another object of the present invention to provide a composite magnetic head which can produce a read output with an excellent S/N ratio even if the head touch is not satisfactory and crosstalk is great.
It is still another object of the present invention to provide a compact composite magnetic head which can satisfactorily read and write various information such as image information, which can re-write information immediately after writing it, which realizes a read system with an exceptionally wide band and low noise, which can suppress degradation in frequency characteristics due to increases in external noise, stray capacitance, or lead inductance, and which is easy to manufacture.